Various monitoring techniques have been used to remotely monitor the security status of an object. For example, a closed circuit television system can be set up to monitor an area in which the object is located. The television output may be monitored manually or by computer to detect unauthorized activity or changes in the television picture, indicating intrusion or movement of the object. However, these systems are expensive, in that a separate camera and/or receiver may be needed for each object or area that is kept under surveillance.
Alternatively, an object (such as a door or window) can be wired to a control panel or a central station in such a way that a signal is generated when the window or door position is changed. Such wiring is often expensive, and it is difficult to relocate the object without rewiring the security system. If a wireless communication system is used, the transmitter that monitors the door or window is typically expensive, due in part to the fact that a power source must be included to operate the transmitter, and due in part to the complexities of the transmitter itself.
U.S. Pat. No. 5,528,222 issued to Moskowitz et. al on Jun. 18, 1996 discloses a radio frequency circuit and memory in a thin flexible package. This type of device is sometimes referred to as a "radio tag". Moskowitz mentions that the radio tag device includes a semiconductor circuit with logic, memory, and so on. He contemplates using the radio tag in conjunction with credit cards, passports, admission tickets and stamps, but does not show or suggest any arrangement which would disable the radio tag as a result of tampering, allowing that device to be used for remote monitoring of the status of objects to which the device is attached.
In its annual report for 1996, Gemplus, a French-based company, describes its Series 200 RF-ID tag, which is a small radio tag device that can be passively read from a remote location. In this report, mention is made of "security schemes", but Gemplus makes no reference to any use of its RF-ID tags in the manner that would provide the desired functionality as is discussed above.